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EDE5104AJSE, EDE5108AJSE, EDE5116AJSE
Data Sheet E1043E40 (Ver. 4.0)
57
Precharge Command [PRE]
The precharge command is used to precharge or close a bank that has been activated. The precharge command is
triggered when /CS, /RAS and /WE are low and /CAS is high at the rising edge of the clock. The precharge
command can be used to precharge each bank independently or all banks simultaneously. Three address bits A10,
BA0 and BA1 are used to define which bank to precharge when the command is issued.
[Bank Selection for Precharge by Address Bits]
A10
BA0
BA1
Precharged Bank(s)
L
L
L
Bank 0 only
L
H
L
Bank 1 only
L
L
H
Bank 2 only
L
H
H
Bank 3 only
H
×
×
All banks 0 to 3
Remark: H: VIH, L: VIL,
×
: VIH or VIL
Burst Read Operation Followed by Precharge
Minimum read to precharge command spacing to the same bank = AL + BL/2 clocks
For the earliest possible precharge, the precharge command may be issued on the rising edge that is
“Additive latency (AL) + BL/2 clocks” after a Read command. A new bank active (command) may be issued to the
same bank after the RAS precharge time (tRP). A precharge command cannot be issued until tRAS is satisfied.
NOP
CK
/CK
T0
T1
T2
T3
T4
T5
T6
T7
T8
Command
DQS, /DQS
DQ
RL = 4
AL = 1
CL = 3
out0
out2
PRE
NOP
out1
out3
Posted
READ
NOP
≥
tRP
≥
tRAS
ACT
AL + BL/2 clocks
Burst Read Operation Followed by Precharge (RL = 4, BL = 4 (AL=1, CL=3))
NOP
CK
/CK
T0
T1
T2
T3
T4
T5
T6
T7
T8
Command
DQS, /DQS
DQ
RL = 5
AL = 2
CL = 3
out0
out2
NOP
PRE
out1
out3
Posted
READ
ACT
NOP
AL + /BL2 clocks
≥
tRP
≥
tRAS(min.)
Burst Read Operation Followed by Precharge (RL = 5, BL = 4 (AL=2, CL=3))